Clamp for clamping a workpiece

Abstract

A clamp for clamping a workpiece such as a forging of an aerofoil component comprises a support body 24 to which a clamping member 26 is hinged. The clamping member 26 has a workpiece clamping element 54 having pads 58 for engagement with the workpiece. The workpiece clamping element 54 is pivotable relatively to the clamping member 26 by means of a ball and socket connection including a ball element 40. This enables the workpiece clamping element 54 to self-align with the profile of the workpiece, for example with a surface of the blade 6 of the aerofoil component. In an alterative embodiment, the workpiece clamping element 54 is formed integrally with the clamping member 26, but is connected thereto by a necked region of the clamping member 26 which permits flexure of the workpiece clamping element 54 relatively to the clamping member 26.

We claim:  
     
       1. A clamp for clamping a workpiece, the clamp comprising: 
       a support body;  
       a workpiece supporting element mounted on the support body:  
       a clamping member mounted on the support body for displacement towards and away from the support body;  
       a workpiece clamping element mounted on the clamping member;  
       securing means adapted to retain the clamping member in a clamping position in which, in use, the workpiece clamping element applies a clamping force to a workpiece clamped between the workpiece clamping element and the workpiece supporting element;  
       connecting means which connects the workpiece clamping element to the clamping member for pivoting displacement relatively to the clamping member about axes lying in a plane extending transversely of the line of action of the clamping force, and for linear movement relatively to the clamping member in a direction substantially transverse to the line of action of the clamping force, whereby the workpiece clamping element is self-aligning with the surface of a clamped workpiece, the connecting means having a ball and socket connection which includes a part-spherical ball element mounted on the clamping member and a socket formed in the workpiece clamping element, the part-spherical ball element engaging the socket; and  
       a retaining pin which engages the workpiece clamping member and which extends with clearance through a bore in the workpiece clamping element for retaining the workpiece clamping element on the workpiece clamping member.  
     
     
       2. A clamp as claimed in  claim 1 , in which the pivoting displacement of the workpiece clamping element is limited by contact between the workpiece clamping element and the clamping member. 
     
     
       3. A clamp as claimed in  claim 1 , in which the clamping member is hinged to the support body. 
     
     
       4. A clamp as claimed in  claim 1 , in which resilient means is provided for biasing the workpiece clamping element relatively to the clamping member in the direction of linear movement. 
     
     
       5. A clamp as claimed in  claim 4 , in which the workpiece clamping element has an abutment face for engagement with a surface of a workpiece under the action of the resilient means. 
     
     
       6. A clamp as claimed in  claim 5 , in which the workpiece supporting element has an abutment face for engagement with a surface of a workpiece, the abutment face of the workpiece supporting element being fixed with respect to the workpiece supporting member. 
     
     
       7. A clamp as claimed in  claim 1 , in which the support body is on a fixture which is adapted for releasable fitting to a machine tool. 
     
     
       8. A clamp as claimed in  claim 1 , which is adapted to receive a workpiece in the form of an aerofoil component. 
     
     
       9. A clamp for clamping a workpiece, the clamp comprising: 
       a support body;  
       a workpiece supporting element mounted on the support body:  
       a clamping member mounted on the support body for displacement towards and away from the support body;  
       a workpiece clamping element mounted on the clamping member;  
       securing means adapted to retain the clamping member in a clamping position in which, in use, the workpiece clamping element applies a clamping force to a workpiece clamped between the workpiece clamping element and the workpiece supporting element; and  
       connecting means which connects the workpiece clamping element to the clamping member for pivoting displacement relatively to the clamping member about axes lying in a plane extending transversely of the line of action of the clamping force, the connecting means comprising a necked region formed integrally with and extending between the clamping member and the workpiece clamping element, the workpiece clamping element projecting on all sides beyond the necked region, whereby the workpiece clamping element is self-aligning with the surface of a clamped workpiece.  
     
     
       10. A clamp as claimed in  claim 9 , in which the pivoting displacement of the workpiece clamping element is limited by contact between the workpiece clamping element and the clamping member. 
     
     
       11. A clamp as claimed in  claim 9 , in which the clamping member is hinged to the support body. 
     
     
       12. A clamp as claimed in  claim 9 , in which the necked region is defined by slots extending inwardly from the outer surface of the clamping member. 
     
     
       13. A clamp as claimed in  claim 9 , in which each slot has a width which is not greater than 0.5 mm. 
     
     
       14. A clamp as claimed in  claim 9 , in which the cross-sectional area of the necked region is not greater than 20 mm 2 . 
     
     
       15. A clamp as claimed in  claim 9 , in which the maximum pivoting angle of the workpiece clamping element relatively to the workpiece clamping member is not greater than 2°. 
     
     
       16. A clamp as claimed in  claim 9 , in which the support body comprises a locating element which is spaced from the workpiece supporting element, which locating element is adapted to engage a region of the workpiece to locate the workpiece on the support body. 
     
     
       17. A clamp as claimed in  claim 16 , in which the locating element comprises a recess adapted to receive a protrusion on the workpiece. 
     
     
       18. A clamp as claimed in  claim 9 , in which the support body is mounted on a fixture which is adapted for releasable fitting to a machine tool. 
     
     
       19. A clamp as claimed in  claim 9 , which is adapted to receive a workpiece in the form of an aerofoil component. 
     
     
       20. A method of performing operations on a workpiece, which method comprises: 
       securing the workpiece in a clamp comprising:  
       a support body;  
       a workpiece supporting element mounted on the support body:  
       a clamping member mounted on the support body for displacement towards and away from the support body;  
       a workpiece clamping element mounted on the clamping member;  
       securing means adapted to retain the clamping member in a clamping position in which the workpiece clamping element applies a clamping force to the workpiece clamped between the workpiece clamping element and the workpiece supporting element; and  
       connecting means which connects the workpiece clamping element to the clamping member for pivoting displacement relatively to the clamping member about axes lying in a plane extending transversely of the line of action of the clamping force, and for linear movement relatively to the clamping member in a direction substantially transverse to the line of action of the clamping force, whereby the workpiece clamping element is self-aligning with the surface of a clamped workpiece, the connecting means having a ball and socket connection which includes a part-spherical ball element mounted on the clamping member and a socket formed in the workpiece clamping element, the part-spherical ball element engaging the socket: and  
       a retaining pin which engages the workpiece clamping member and which extends with clearance through a bore in the workpiece clamping element for retaining the workpiece clamping element on the workpiece clamping member; and  
       performing the operation on the clamped workpiece.  
     
     
       21. A method of performing operations on a workpiece, which method comprises: 
       securing the workpiece in a clamp comprising:  
       a support body;  
       a workpiece supporting element mounted on the support body:  
       a clamping member mounted on the support body for displacement towards and away from the support body;  
       a workpiece clamping element mounted on the clamping member;  
       securing means adapted to retain the clamping member in a clamping position in which the workpiece clamping element applies a clamping force to the workpiece clamped between the workpiece clamping element and the workpiece supporting element; and  
       connecting means which connects the workpiece clamping element to the clamping member for pivoting displacement relatively to the clamping member about axes lying in a plane extending transversely of the line of action of the clamping force, the connecting means comprising a necked region formed integrally with and extending between the clamping member and the workpiece clamping element, the workpiece clamping element projecting on all sides beyond the necked region, whereby the workpiece clamping element aligns with the surface of the clamped workpiece; and  
       performing the operations on the clamped workpiece.